Recording apparatus and recording method

ABSTRACT

A recording apparatus includes a recording head that includes a plurality of recording devices containing ink, first and second heating devices, and first and second detection devices. The recording devices each generate energy for ejection of the ink, the first and second heating devices respectively heat the ink in a vicinity of recording devices located at first and second positions of the recording devices, and the first and second detection devices respectively detect temperatures in the vicinity of the recording devices located at the first and second positions. The recording apparatus includes an acquisition unit configured to acquire information relating to a representative temperature of the temperatures detected by the first and second detection devices, and a decision unit configured to decide an upper limit of driving power of each of the first and second heating devices.

BACKGROUND Field

The present disclosure relates to a recording apparatus and a recordingmethod.

Description of the Related Art

There is a recording apparatus that records an image using a recordinghead, the recording head including a substrate in which a plurality ofrecording devices generating heat energy for ejection of ink isprovided. In such a recording apparatus, if a temperature in thevicinity of the recording devices significantly decreases, an inkejection amount may be excessively reduced, which may lower density ofthe image to be recorded.

To prevent the ejection amount from excessively decreasing due to atemperature drop as described above, in Japanese Patent ApplicationLaid-Open No. 3-005151, a recording head is used that includes, inaddition to the recording devices, a detection device that detects atemperature in the vicinity of the recording devices and a heatingdevice that heats the vicinity of the recording devices. If the heatingdevice and the detection device are used, the heating device can bedriven to heat the vicinity of the recording device in the case wherethe temperature detected by the detection device becomes lower than athreshold; such a process makes it possible to suppress theabove-described density lowering.

In the case of using the above-described recording head, the temperaturedetected by the detection device may be higher than the actualtemperature of the ink in the recording apparatus in some cases. Such agap between the detected temperature and the actual temperature mayappear, for example, in a case where an ink tank is placed in alow-temperature environment before being attached to the recordingapparatus, and the low-temperature ink is supplied to the vicinity ofthe recording devices in the recording.

When heat control discussed in Japanese Patent Application Laid-Open No.3-005151 is performed, the detection device may detect relatively hightemperature because of the detection device being located near theheating device. However, in a case where, outside the recording head,for example, the ink tank is placed in a low-temperature environment,the temperature of the ink inside the ink tank can become low due toinfluence of the low-temperature environment because heating is notperformed near the ink tank. In other words, in some circumstances, thetemperature detected by the detection device may be high due toinfluence of the heat control, while at the same time the temperature ofthe ink supplied from the ink tank may be low. Accordingly, although itmay, in fact, be necessary to perform heat control because the actualtemperature of the ink near the recording devices is low, heat controlmay not be performed because the detection device detects a temperaturethat is high.

To address this problem, the fixed temperature threshold used in theheat control may be set to a lower value so that heat control is alsoperformed at the low temperature, anticipating that the detectedtemperature is higher than the actual temperature. In this case,however, the heat control may frequently be performed even in a casewhere a gap between the detected temperature and the actual temperaturedoes not appear, which may unnecessarily increase driving power of theheating device.

The power consumed for recording by the recording head is mainlyseparated into driving power to drive the recording devices for ejectionof the ink and driving power to drive the above-described heatingdevice. The consumable power has an upper limit. Therefore, if thedriving power of the heating device is unnecessarily increased, thetotal power consumption combining the driving power of the recordingdevices and the driving power of the heating device may exceed the upperlimit, which may damage the recording head, a heater board, wirings,etc.

Besides, with respect to unnecessary driving power that may arise whenthe heating operation is performed in the heating device, a maximumvalue may be previously estimated, and the driving of the recordingdevices may be regulated so as to prevent the power consumption in therecording by the recording head from reaching the upper power limit, byobtaining maximum value previously. This, however, may unnecessarilyreduce the driving power of the recording devices, by theabove-described maximum value in the case where the detection error doesnot occur. When the number of ejections of the ink to a recording mediumis increased scanning speed of the recording head is increased, it isnecessary to increase the driving power of the recording devices;however, the driving power of the recording devices may becomeinsufficient if the above-described method is employed, which may reducethe number of ejections or the recording speed, for example.

SUMMARY

The present disclosure is directed to suppressing excess powerconsumption and preventing driving power of a recording device frombecoming insufficient even if detected temperature deviates from actualtemperature in a heating operation by a heating device.

According to various embodiments of the present disclosure, a recordingapparatus includes a recording head that includes a plurality ofrecording devices containing ink, first and second heating devices, andfirst and second detection devices. The recording devices each generateenergy for ejection of the ink, the first and second heating devicesrespectively heat the ink in a vicinity of recording devices located atfirst and second positions of the recording devices, and the first andsecond detection devices respectively detect temperatures in thevicinity of the recording devices located at the first and secondpositions. The recording apparatus includes an acquisition unitconfigured to acquire information relating to a representativetemperature of the temperatures detected by the first and seconddetection devices, a determination unit configured to determine whetherthe representative temperature or a first temperature threshold ishigher, a decision unit configured to decide an upper limit of drivingpower of each of the first and second heating devices, based on adetermination result of the determination unit, a recording control unitconfigured to drive the recording devices to control a recordingoperation, and a heat control unit configured to drive each of the firstand second heating devices to control a heating operation during therecording operation, based on the temperatures respectively detected bythe first and second detection devices and a second temperaturethreshold that is higher than the first temperature threshold. The heatcontrol unit drives the first and second heating devices to cause thedriving power to be lower than the decided upper limit indicated by therepresentative temperature related information. The decision unitdecides the upper limit (i) so as to increase the upper limit in a casewhere the determination unit determines one time that the representativetemperature is lower than the first temperature threshold, and (ii) soas to decrease the upper limit in a case where the determination unitconsecutively determines N(N≥2) times that the representativetemperature is higher than the first temperature threshold.

Further features will become apparent from the following description ofexemplary embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an internal configuration of arecording apparatus according to an exemplary embodiment.

FIG. 2 is a diagram illustrating a recording head according to theexemplary embodiment.

FIGS. 3A to 3C are diagrams each illustrating a heater board accordingto the exemplary embodiment.

FIG. 4 is a diagram illustrating a circulation configuration accordingto the exemplary embodiment.

FIG. 5 is a diagram illustrating a recording control system according tothe exemplary embodiment.

FIG. 6 is a flowchart illustrating temperature-retention controlaccording to the exemplary embodiment.

FIGS. 7A and 7B are diagrams illustrating correspondence between atemperature difference and a sub-heater (SH) rank according to theexemplary embodiment.

FIG. 8 is a diagram illustrating correspondence between the SH rank anddriving information according to the exemplary embodiment.

FIG. 9 is a flowchart illustrating an upper limit calculation methodaccording to the exemplary embodiment.

FIG. 10 is a flowchart illustrating pre-heating control according to theexemplary embodiment.

FIG. 11 is a diagram illustrating an SH rank correction value accordingto the exemplary embodiment.

FIG. 12 is a flowchart illustrating a speed setting method according tothe exemplary embodiment.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a diagram illustrating an internal configuration of an inkjetrecording apparatus (hereinafter, also referred to as recordingapparatus) according to an exemplary embodiment.

A recording medium P fed from a feeding unit 101 is conveyed in +Xdirection (conveyance direction, intersecting direction) at apredetermined speed while being pinched by conveyance roller pairs 103and 104 to be discharged to a discharging unit 102. Recording heads 105to 108 are arranged side by side along the conveyance direction betweenthe conveyance roller pair 103 on an upstream side and the conveyanceroller pair 104 on a downstream side, and each eject ink in Z directionaccording to recording data. The recording heads 105, 106, 107, and 108respectively eject the ink of cyan, magenta, yellow, and black. Each ofthe ink is held in a corresponding ink tank (not illustrated) that isdetachable from the recording apparatus, and each of the ink is suppliedto the recording heads 105 to 108 through a tube (not illustrated) fromthe ink tank.

In the present exemplary embodiment, the recording medium P may be acontinuous sheet that is held in a roll shape by the feeding unit 101,or may be a cut sheet previously cut in a standard size. In a case ofthe continuous sheet, the sheet is cut into a predetermined length by acutter 109 after recording operation by the recording heads 105 to 108is completed, and the cut sheet is divided into discharge trays forrespective sizes by the discharging unit 102.

(Recording Head)

FIG. 2 is a diagram illustrating a configuration of the recording head105 for cyan ink used in the present exemplary embodiment. In thefollowing description, only the recording head 105 out of the recordingheads 105 to 108 is described for simplification; however, the recordingheads 106 to 108 other than the recording head 105 also have aconfiguration similar to the configuration of the recording head 105.

As illustrated in FIG. 2, in the present exemplary embodiment, therecording head 105 includes 15 heater boards (recording devicesubstrates) HB0 to HB14. The heater boards are arranged side by sidealong Y direction such that end parts of the respective heater boards inthe Y direction partially overlaps with one another. By using therecording head in which the 15 heater boards HB0 to HB14 are arranged inthe Y direction in such a manner, recording can be performed on anentire region of the recording medium that has a long width in the Ydirection, as with a case of using a single elongated recording head.

FIG. 3A is a diagram illustrating a configuration of the heater boardHB0 out of the heater boards HB0 to HB14. In this example, the heaterboard HB0 is described; however, the other heater hoard HB1 to HB14 alsohave a similar configuration.

As illustrated in FIG. 3A, the heater board HB0 includes an ejectionport array 21 in which ejection ports for ejecting the cyan ink arearranged in the Y direction.

The heater board HB0 further includes five temperature sensors(detection devices) 24 a to 24 e and five sub-heaters (heating devices)23 a to 23 e. The temperature sensor 24 a and the sub-heater 23 a areprovided at positions near an upstream end part of the ejection portarray 21 in the Y direction. In other words, the temperature sensor 24 adetects a temperature of a region near an ejection port part 22 a at theupstream end part of the ejection port array 21 in the Y direction, andthe sub-heater 23 a is used to heat the region near the ejection portpart 22 a. Likewise, in the ejection port array 21, the temperaturesensor 24 b and the sub-heater 23 b correspond to an ejection port part22 b which is adjacent to the ejection port part 22 a, and arerespectively used for temperature detection and heating of the ejectionport part 22 b. Likewise, the temperature sensor 24 c and the sub-heater23 c correspond to an ejection port part 2 c, the temperature sensor 24d and the sub-heater 23 d correspond to an ejection port part 22 d, andthe temperature sensor 24 e and the sub-heater 23 e correspond to anejection port part 22 e illustrated in FIG. 3A.

Thus, the ejection port array 21 in the heater board HB0 is divided intothe five ejection port parts 22 a to 22 e, and temperature detection andheating are individually performed on each of the ejection port parts asdescribed below. As described above, the recording head 105 for cyan inkincludes the 15 heater boards HB0 to HB14. Accordingly, a total of 300(=5×15×4) temperature sensors and 300 sub-heaters are provided for fourcolors. The temperature detection and heating can be individuallycarried out on 300 ejection port parts corresponding to the 300temperature sensors and the 300 sub-heaters.

FIG. 3B is an enlarged view illustrating a side where a part of theejection ports of the ejection port array 21 is formed in the heaterboard HB0.

As illustrated in FIG. 3B, recording devices 11 are disposed atpositions corresponding to ejection ports 12 constituting the ejectionport array 21. When a driving pulse is applied to the recording devices11, each of the recording devices 11 is driven and generates heatenergy, makes the ink foamed by the heat energy, and performs ejectionoperation through the corresponding ejection port 12. The recordingdevices 11 are provided inside pressure chambers 13 that are defined bypartition walls. Further, ink supply ports 14 are provided in thedirection of the ejection port array 21, and ink collection ports 15 areprovided in −X direction of the ejection port array 21. Morespecifically, as illustrated in FIG. 3B, one ink supply port and one inkcollection port 15 are provided for two ejection ports 12.

FIG. 3C is a cross-sectional view when a region inside the heater boardHB0 illustrated in FIG. 3B is cut along a direction intersecting an XYplane.

As illustrated in FIG. 3C, the heater board HB0 includes three layers.More specifically, an ejection port forming member 18 formed of aphotosensitive resin is stacked on a substrate 19 formed of silicon(Si), and a supporting member 20 is bonded to rear side of the substrate19.

The above-described ejection ports 12 are provided on front side of theejection port forming member 18. Further, the pressure chambers 13 thatcommunicate with the ejection ports 12 are provided inside the ejectionport forming member 18.

The above-described recording devices 11 are disposed on front side(ejection port forming member 18 side) of the substrate 19, and a commonink supply path 16 and a common ink collection path 17 are providedinside the substrate 19. Further, the ink supply ports 14 are providedso as to connect the common ink supply path 16 and the pressure chambers13 inside the ejection port forming member 18, and the ink collectionports 15 are provided so as to connect the common ink collection path 17and the pressure chambers 13 inside the ejection port forming member 18.

The common ink supply path 16 and the common ink collection path 17 areprovided over the entire region where the ejection ports 12 are arrangedin the Y direction. Further, as described below, the common ink supplypath 16 and the common ink collection path 17 are controlled to generatenegative pressure difference therebetween. Accordingly, when the ink isejected from a part of the ejection ports 12 in the recording operation,the ink inside the common ink supply path 16 flows, due to the negativepressure difference, to the common ink collection path 17 through theink supply ports 14, the pressure chambers 13, and the ink collectionports 15 in the ejection ports 12 that is not performing ejection (arrowin FIG. 3C). This flow allows for collection of thickened ink arisingfrom evaporation from the ejection ports 12, bubbles, foreign matters,etc. that are generated in the ejection ports 12 and the pressurechambers 13 to, to the common ink collection path 17.

Further, the supporting member 20 functions as a lid that forms a partof a wall of the common ink supply path 16 and the common ink collectionpath 17 inside the substrate 19.

(Circulation Configuration)

FIG. 4 is a schematic view illustrating a circulation configuration of acirculation path employed in the present exemplary embodiment. For thesake of simplicity, only the circulation path in the recording head 105of the recording heads 105 to 108 is described; however, the circulationpath in any of the other recording heads 106 to 108 has a similarconfiguration.

The recording head 105 is fluidically connected to a first circulationpump (P2) 1001 an a high-pressure side, a second circulation pump (P3)1002 on a low-pressure side, and a main tank (ink tank) 1003. The maintank 1003 can discharge air bubbles the ink to the outside via anatmosphere communication port (not illustrated), through which theinside of the main tank 1003 is communicated with the outside. The inkinside the main tank 1003 is consumed in recording an image andperforming recovery processing (including preliminary ejection, suctiondischarge, pressurization discharge, etc.), and the empty main tank 1003is removed from the recording apparatus and is replaced.

As described above, the common ink supply path 16 and the common inkcollection path 17 are provided in each of the heater boards HB0 to HB14inside the recording head 105, and the pressure chambers 13 thatcommunicate with one another through the ink supply ports 14 and the inkcollection ports 15 are provided between the common ink supply path 16and the common ink collection path 17. For the sake of simplicity, onlythe heater board HB0 of the heater boards HB0 to HB14 is illustrated inFIG. 4; however, the heater boards HB0 to HB14 are actually connected inseries to one another. The heater board HB0 is located on the mostupstream side (right side in FIG. 4), and the heater board HB14 islocated on the most downstream side (left side in FIG. 4) in an inkcirculation direction. The heater boards HB0 to HB14 are arranged inascending order toward the downstream.

The first circulation pump 1001 sucks the ink inside the common inksupply path 16 through a connection portion 111 a of a negative-pressurecontrol unit 230 and an outlet 211 b of the recording head 105, andreturns the sucked ink to the main tank 1003. The second circulationpump 1002 sucks the ink inside the common ink collection path 17 througha connection portion 111 b of the negative-pressure control unit 230 andan outlet 212 b of the recording head 105, and returns the sucked ink tothe main tank 1003. A positive-displacement pump having quantitativeliquid feeding ability is preferably used as the first circulation pump1001 and the second circulation pump 1002. Specific examples of thepositive-displacement pump are a tube pump, a gear pump, a diaphragmpump, and a syringe pump, etc. Moreover, a general constant flow valveor a general relief valve may be provided at an outlet of the pump tosecure a constant flow rate.

When the recording head 105 is driven, a constant amount of ink flowsthrough the common ink supply path 16 in an arrow A direction (supplydirection) in FIG. 4 by the first circulation pump 1001, and flowsthrough the common ink collection path 17 in an arrow B direction(collection direction) in FIG. 4 by the second circulation pump 1002.The flow rate can be set to a low rate at which temperature differencesamong the heater boards HB0 to HB14 are suppressed to an extent whichdoes not influence image quality of the recorded image. If the flow rateis excessively large, the negative pressure difference in each of theheater boards HB0 to HB14 may become excessively large due to influenceof pressure loss of the flow path inside the recording head 105, whichmay cause density unevenness of the recorded image. Accordingly, theflow rate of the ink inside the common ink supply path 16 and the commonink collection path 17 is preferably set in consideration of thetemperature difference and the negative-pressure difference among theheater boards HB0 to HB14.

The negative-pressure control unit 230 is provided in a flow pathbetween a third circulation pump (P1) 1004 and the recording head 105.The negative-pressure control unit 230 includes a function ofmaintaining constant pressure of the ink on the recording head 105 sideeven in a case where the flow rate of the ink in an ink circulationsystem is varied according to the density (election amount) of therecorded image. Two pressure regulation mechanisms 230 a and 230 bconstituting the negative-pressure control unit 230 may be anymechanisms as long as they can control the pressure in the flow path onthe downstream of the mechanism to be within a fixed range centering ona desired setting pressure. As an example, a mechanism similar to thatof a so-called depressurization regulator can be adopted. In a case ofusing the depressurization regulator, the inside of the upstream flowpath of the negative-pressure control unit 230 is preferably pressurizedthrough an ink supply unit 220 by the third circulation pump 1004 asillustrated in FIG. 4. Thus, influence of water head pressure betweenthe main tank 1003 and the recording head 105 on the recording head 105can be suppressed, and flexibility of the layout of the main tank 1003can be enhanced in the recording apparatus. The third circulation pump1004 is connected to the pressure regulation mechanisms 230 a and 230 bthrough the connection portion 111 b of the negative-pressure controlunit 230 and a filter 221. It is sufficient for the third circulationpump 1004 to have head pressure equal to or higher than a predeterminedpressure within a range of the circulation flow rate of the ink when therecording head 105 is driven, and for example, a turbo pump or apositive-displacement pump may be used as the third circulation pump1004. For example, a diaphragm pump is employable. Further, in place ofthe third circulation pump 1004, a water-head tank that is disposed witha predetermined water head difference with respect to thenegative-pressure control unit 230, is employable.

Different control pressure is set to the two pressure regulationmechanisms 230 a and 230 b in the negative-pressure control unit 230.The pressure regulation mechanism 230 a is denoted by “H” in FIG. 4because the pressure regulation mechanism 230 a is set to relativelyhigh pressure, and the pressure regulation mechanism 230 b is denoted by“L” in FIG. 4 because the pressure regulation mechanism 230 b is set torelatively low pressure. The pressure regulation mechanism 230 a isconnected to an inlet 211 a of the common ink supply path 16 of therecording head 105 through the inside of the ink supply unit 220. Thepressure regulation mechanism 230 b is connected to an inlet 212 a ofthe common ink collection path 17 of the recording head 105 through theinside of the ink supply unit 220.

The pressure regulation mechanism 230 a on the high-pressure side isconnected to the inlet 211 a of the common ink supply path 16, and thepressure regulation mechanism 230 b on the low-pressure side isconnected to the inlet 212 a of the common ink collection path 17.Therefore, the negative pressure difference occurs between the commonink supply path 16 and the common ink collection path 17. Accordingly, apart of the ink flowing inside the common ink supply path 16 in thearrow A direction and a part of the ink flowing inside the common inkcollection path 17 in the arrow B direction flow through the ink supplyports 14, the pressure chambers 13, and the ink collection ports 15 inan arrow C direction.

As described above, in the recording head 105, the ink flows through thecommon ink supply path 16 in the arrow A direction and the common inkcollection path 17 in the arrow B direction in each of the heater boardsHB0 to HB14. Accordingly, heat generated in each of the heater boardsHB0 to HB14 is discharged to the outside while the ink flows through theinside of the common ink supply path 16 and the common ink collectionpath 17. In addition, such a configuration causes the flow of the inkalso in the ejection ports 12 not ejecting the ink and the pressurechambers 13 in the arrow C direction during the recording operation, andsuppresses thickening of the ink in such ejection ports 12 and pressurechambers 13. Moreover, the thickened ink and the foreign matters in theink are discharged to the outside through the common ink collection path17. As a result, it is possible to perform high-speed recording of ahigh-quality image with use of the recording head 105.

(Recording Control System)

FIG. 5 is a diagram illustrating a configuration of a recording controlsystem in the recording apparatus according to the present exemplaryembodiment. For the sake of simplicity, only the recording controlsystem relating to the recording head 105 of the recording heads 105 to108 is described.

As illustrated in FIG. 5, the recording apparatus includes an encodersensor 301, a dynamic random access memory (DRAM) 302, a read onlymemory (ROM) 303, a controller (application specific integrated circuit(ASIC)) 304, and the recording heads 105 to 108.

The controller 304 includes a recording data generation unit 305, acentral processing unit (CPU) 306, an ejection timing generation unit307, a temperature value storage memory 308, a sub-heater table storagememory 314, and data transfer units 310 to 313.

The CPU 306 reads a program stored in the ROM 303 to execute theprogram, and controls operation of the entire recording apparatus, forexample, actuates a driver of each motor. Further, the ROM 303 holdsfixed data necessary for various kinds of operation of the recordingapparatus, in addition to the various kinds of control programs to beexecuted by the CPU 306. For example, the ROM 303 stores a program usedto perform recording control in the recording apparatus.

The DRAM 302 is necessary for execution of the program by the CPU 306,and is used as a work area of the CPU 306 or as a temporal storageregion of various reception data, or holds various kinds of settingdata. While in FIG. 5, only one DRAM 302 is described, a plurality ofDRAMs may be mounted, or a plurality of memories with different accessspeed may be mounted, which includes both of the DRAM and a staticrandom access memory (SRAM).

The recording data generation unit 305 receives the image data from ahost (personal computer (PC)) outside the recording apparatus. Therecording data generation unit 305 performs color conversion processing,quantization processing, etc. on the image data, generates the recordingdata used for ejection of the ink from each of the recording heads 105to 108, and stores the recording data in the DRAM 302.

The ejection timing generation unit 307 receives position informationthat indicates a relative position between each of the recording heads105 to 108 and the recording medium P, detected by the encoder sensor301. The ejection timing generation unit 307 generates ejection timinginformation that indicates timing of ejection of each of the recordingheads 105 to 108, based on the position information.

The four data transfer units 310 to 313 read the recording data storedin the DRAM 302 at the ejection timing generated by the ejection timinggeneration unit 307. Further, the four data transfer units 310 to 313generate sub-heater driving information in each of the heater boards HB0to HB14 of each of the recording heads 105 to 108 held in thetemperature value storage memory 308, based an temperature informationheld by the temperature value storage memory 308. The data transferunits 310 to 313 respectively transfer the recording data and thesub-heater driving information to the recording heads 105 to 108.

The recording heads 105 to 108 drive the recording devices to eject theink with use of the transferred recording data, and provide thetemperatures detected by the temperature sensors of the heater boards inthe recording heads 105 to 108, to a heat control unit 309 inside therecording apparatus in the present exemplary embodiment, as describedabove, one heater board includes five temperature sensors, one recodinghead includes 15 heater boards, and the recording heads are provided forfour colors. Therefore, a total of 300 (=5×15×4) temperature sensors areprovided, and 300 pieces of temperature information are provided to theheat control unit 309. The heat control unit 309 stores in thetemperature value storage memory 308 the temperature informationrelating to the newly-detected temperature, and updates the temperatureinformation. The updated temperature information is used at next timingof generating the sub-heater driving information.

(Temperature-Retention Control)

Temperature-retention control (sub-heater heat control) executed in thepresent exemplary embodiment is described in detail. In thetemperature-retention control according to the present exemplaryembodiment, the sub-heaters are driven to heat the ink near therecording devices and the temperature of the ink is retained in order toprevent the temperature near the recording devices from becoming lowtemperature which influences the ink election when the recording devicesare driven to perform the ejection operation of the ink. In thefollowing description, only the recording head 105 of the recordingheads 105 to 108 is described for the sake of simplicity.

FIG. 6 is a flowchart of the temperature-retention control (sub-heaterheat control) executed by the heat control unit 309 according to thecontrol program in the present exemplary embodiment.

First, in step S1, the temperatures detected by the temperature sensors24 a to 24 e provided in each of the heater boards HB0 to HB14 insidethe recording head 105 are acquired. As described above, the detectedtemperatures are held in the temperature value storage memory 308.

Next, in step S2, a difference (temperature difference) ΔT between eachdetected temperature and a predetermined target temperature T1 iscalculated. More specifically, the temperature different ΔT iscalculated by subtracting each detected temperature from the targettemperature T1. The target temperature T1 corresponds to a temperaturewhen the vicinity of the recording devices is heated to an extent whichdoes not influence ejection of the ink, and the target temperature T1 isset to 40° C. in the present exemplary embodiment.

Next, in step S3, a sub-heater rank (hereinafter, also referred to as SHrank) indicating driving strength of the sub-heaters is selectedaccording to the value of the temperature difference ΔT, with referenceto the sub-heater table storage memory 314. The SH rank is selected foreach of the sub-heaters 23 a to 23 e of the heater boards HB0 to HB14,based on the temperature difference ΔT in the temperature sensors 24 ato 24 e of the heater boards HB0 to HB14. In other words, since 75(=5×15) sub-heaters are provided in the recording head 105, 75 SH ranksare individually selected. The temperature difference ΔT and the SH rankare associated with each other such that the sub-heater driving strengthbecomes larger as the temperature difference ΔT is larger. This isbecause the driving energy to be applied to the sub-heaters until thetemperature reaches the target temperature T1 becomes larger as thedetected temperature becomes lower compared with the target temperatureT1.

FIG. 7A illustrates correspondence between the temperature difference ΔTand the SH rank according to the present exemplary embodiment. Thelarger SH rank, the larger sub-heater driving strength as shown in FIG.7A. For example, when the temperature difference ΔT is lower than zero,the minimum SH rank “0” is selected because the detected temperature ishigher than the target temperature T1. The SH rank “0” corresponds tonon-driving of the sub-heater as described below. Further, for example,when the temperature difference ΔT is a large value equal to or higherthan 2.0, the maximum SH rank “31” is selected because the detectedtemperature is significantly lower than the target temperature T1. TheSH rank “31” substantially corresponds to driving the sub-heater all thetime as described below.

Next, in step S4, the SH rank that has been selected for each of thesub-heaters 23 a to 23 e of the heater boards HB0 to HB14 in step S3 iscorrected based on a temperature-retention upper limit S1. Thetemperature-retention upper limit S1 corresponds to an upper limit ofthe driving power which can be supplied to the sub-heater at that time,and is generated according to a flowchart described below.

Correction of the SH rank in step S4 in a case where the upper limit is“21” is now described. FIG. 7B illustrates the SH rank corresponding tothe temperature difference ΔT after the correction is made in step S4 inthe case where the upper limit is “21”. In the present exemplaryembodiment, in a case where the temperature difference ΔT is lower thanzero, zero or higher and lower than 0.5, 0.5 or higher and lower than1.0, or 1.0 or higher and lower than 1.5, the SH rank in step S3 is “0”,“6”, “12”, or “18”, respectively, therefore, is lower than the upperlimit “21”. Accordingly, the correction is not performed on the SH rankin step S4. On the other hand, in a case where the temperaturedifference ΔT is 1.5 or higher and lower than 2.0, or 2.0 or higher, theSH rank is “24” or “31”, respectively, in step S3, and is higher thanthe upper limit “21”. Accordingly, in these cases, since the drivingpower exceeds the driving power which can be supplied to the sub-heater,the SH rank is corrected to “21”.

In step S5, the sub-heaters 23 a to 23 e of the heater boards HB0 toHB14 are driven based on the SH ranks determined in steps S3 and S4. Atthis time, the sub-heater driving information corresponding to the SHrank is output with reference to the sub-heater table storage memory314.

FIG. 8 is a diagram illustrating correspondence between the SH rank andthe sub-heater driving information according to the present exemplaryembodiment. FIG. 8 shows how many times a signal “1” which indicatesdriving of the sub-heater and a signal “0” which indicates non-drivingof the sub-heater are input, of 32 timings at which the sub-heaterdriving information can be input, for each of the SH ranks.

For example, in a case of the SH rank “0”, it can be seen from a top rowof FIG. 8 that the signal “0” indicating non-driving of the sub-heateris set in each of the sub-heater driving timings “0” to “31.Accordingly, when the SH rank is “0”, the sub-heater is not driven evenone time at 32 timings.

In a case of the SH rank “31”, it can be seen from a bottom row of FIG.8 that the signal “1” indicating driving of the sub-heater is set insub-heater driving timings “0” to “30”, and the signal “0” indicatingnon-driving of the sub-heater is set at timing “31”. Accordingly, whenthe SH rank is “31”, the sub-heater is driven 31 times of 32 timings.

As described above, it is possible to increase the number of drivingtimes of the sub-heaters, namely, to increase the driving strength asthe SH rank becomes larger, based on the correspondence illustrated inFIG. 8.

(Upper Limit Calculation Processing)

In the present exemplary embodiment, the temperature-retention upperlimit S1 used in the above-described temperature-retention control isnot fixed to a predetermined value but is varied according topredetermined timing.

In the recording apparatus, it is possible to accurately predict thedriving power of the sub-heaters in the temperature-retention control ifdetection error does not occur in each of the temperature sensors 24 ato 24 e within the heater boards HB0 to HB14 of the recording heads 105to 108. The power consumption that may vary during the predeterminedoperation relating to the recording heads 105 to 108 is mainly thedriving power of the recording devices and the driving power of thesub-heaters. Therefore, if the driving power of the sub-heaters ispredicted, it is possible to preset the driving power of the recordingdevices for the ejection operation, based on the driving power of thesub-heaters. Further, the recording apparatus is designed such that thedriving power of the sub-heaters does not become so large in thetemperature-retention control when the temperature is within the normaltemperature range. Accordingly, a leeway can be comparatively given tothe power used for driving the recording devices.

In a case where an error occurs and the detected temperature is lowerthan the actual temperature inside the recording apparatus in thetemperature sensors 24 a to 24 e, however, the power larger thanactually necessary power is used for driving the sub-heaters. In thiscase, the total power consumption of the driving power of the recordingdevices and the sub-heaters may exceed the upper limit of the powerwhich can be supplied to the recording heads 105 to 108, the wirings,etc.

To suppress such excessive power consumption, a fixed value (fixed upperlimit S2 described below) may be set as the upper limit of the drivingpower of the sub-heaters, taking account of the error of the detectedtemperatures that can occur in the temperature sensors 24 a to 24 e. Aswith the present exemplary embodiment, in a case where the driving powerof the sub-heater is tentatively determined based on the temperaturedifference and the tentatively-determined driving power exceeds theupper limit, a correction may be made such that the driving power of thesub-heaters becomes equal to or lower than the upper limit to performthe temperature-retention control.

In this case, however, the upper limit of the driving power of thesub-heaters is set to a relatively large value taking account of thedetection error. Therefore, the power usable for driving the recordingdevices is decreased. As a result, sufficient driving power may not besupplied even when it is necessary to increase the driving power of therecording devices.

Under such circumstances, in the present exemplary embodiment, thetemperature-retention upper limit S1 is varied at the predeterminedtiming as described above, and too much consumption of the driving powerof the sub-heaters, eventually excessive power consumption is suppressedwhile increasing the power used for driving of the recording device asmuch as possible even in the case where detection error occurs.

More specifically, first, the driving power (above-described fixedvalue) of the sub-heaters at which the power consumption does not exceedthe upper limit of the power suppliable to the recording heads 105 to108 and the wirings even when the detection error occurs, is stored asthe fixed upper limit S2. The fixed upper limit S2 is used as thetemperature-retention upper limit S1 of the driving power of thesub-heaters until a certain time elapses after the temperature-retentioncontrol is started.

After that, in a case where the temperatures detected by the temperaturesensors 24 a to 24 e inside the heater boards HB0 to HB14 of therecording heads 105 to 108 are all higher than a retention determinationtemperature T2 for a while, it is determined that the temperature issufficiently retained through the temperature-retention control, and thetemperature-retention upper limit S1 is lowered (decreased).

The retention determination temperature T2 is used to determine whetherthe temperature is retained with the temperature-retention upper limitS1 at that time through the temperature-retention control.

Even in a case where the temperatures in the regions corresponding toeach temperature sensor 24 a to 24 e are not sufficient and thetemperature-retention control is accordingly performed in step S2,temperature can be retained if the temperature is sufficiently increasedto the target temperature through the temperature-retention control withthe temperature-retention upper limit S1 at that time. Therefore, thetemperature-retention upper limit S1 is lowered. Accordingly, it can beseen that the retention determination temperature T2 can be lower thanthe target temperature T1 (40° C.). In the present exemplary embodiment,the retention determination temperature T2 is set to 39° C.

However, it is not possible to determine that the temperature is surelyretained with the temperature-retention upper limit S1 at that time,based on the fact that the minimum temperature Tmin has exceeded theretention determination temperature T2 only one time. The minimumtemperature Tmin barely exceeds the retention determination temperatureT2 with the temperature-retention upper limit S1 at that time. In somecases, when the temperature-retention upper limit S1 is varied even onlya little, the minimum temperature Tmin is decreased and the temperaturemay not be retained sufficiently. Accordingly, if the number(consecutive number) of times N that the minimum temperature Tminconsecutively exceeds the retention determination temperature T2 becomesequal to or larger than a consecutive threshold Nmax, thetemperature-retention upper limit is first decreased. At this time, theconsecutive threshold Nmax may be equal to or higher than two. In thepresent exemplary embodiment, the consecutive threshold Nmax is set totwo.

On the other hand, in a case where the temperature hardly reaches thetarget temperature even when the temperature-retention control isperformed at the temperature-retention upper limit S1 at that time, ifthe temperature-retention upper limit S1 is decreased, the temperaturemay not be suitably retained in spite of the temperature-retentioncontrol. Accordingly, in a case where the temperatures detected by thetemperature sensors 24 a to 24 e become lower than the retentiondetermination temperature T2, the temperature-retention upper limit S1is increased to make the temperatures sufficient.

As described above, in the present exemplary embodiment, thetemperature-retention control is performed while thetemperature-retention upper limit S1 is varied.

FIG. 9 is a flowchart of the upper limit calculation processing executedby the heat control unit 309 according to the control program in thepresent exemplary embodiment.

When the upper limit calculation processing is started, the fixed upperlimit S2, the retention determination temperature T2, and theconsecutive threshold Nmax previously stored in the sub-heater tablestorage memory 314 are read out. The temperature-retention upper limitS1 is equal to the fixed upper limit S2 at a point of time immediatelyafter the upper limit calculation processing is started. Further, thefixed upper limit S2 is a value set taking account of the detectionerror that may occur in the temperature sensors, and corresponds to thedriving power, which is consumable by the sub-heaters.

Next, in step S11, the minimum temperature Tmin of the temperaturesdetected by the temperature sensors 24 a to 24 e within the heaterboards HB0 to HB14 of the recording heads 105 to 108, is acquired.

Next, in step S12, it is determined whether the minimum temperature Tminis lower than the retention determination temperature T2.

In a case where it is determined in step S12 that the minimumtemperature Tmin is equal to or lower than the retention determinationtemperature T2 (Yes in step S12), the processing proceeds to step S13,and it is determined whether the temperature-retention upper limit S1 atthat time is lower than the fixed upper limit S2. Since thetemperature-retention upper limit S1 is equal to the fixed upper limitS2 immediately after the upper limit calculation processing is performedas described above, it is determined that the temperature-retentionupper limit S1 is equal to or larger than the fixed upper limit S2 instep S13.

Next, in a case where it is determined in step S13 that thetemperature-retention upper limit S1 is lower than the fixed upper limitS2 (Yes in step S13), the processing proceeds to step S14, and thetemperature-retention upper limit S1 is incremented by one (added,increased, S1→S1+1). This is because the minimum temperature Tmin islower than the retention determination temperature T2 in step S12, andthe temperature-retention upper limit S1 is lower than the fixed upperlimit S2 even though the region where the heating is insufficientappears at the upper limit at that time. Therefore, it is still possibleto further increment the temperature-retention upper limit S1.

After that, the processing proceeds to step S15 and the consecutivenumber N is reset (initialized, N→zero).

In a case where it is determined in step S13 that thetemperature-retention upper limit S1 is equal to or larger than thefixed upper limit S2 (No in step S13), the processing proceeds to stepS16 without incrementing the upper limit, and the consecutive number Nis incremented (added, increased) by one (N→N+1). Actually, thetemperature-retention upper limit S1 does not become larger than thefixed upper limit S2, and the processing proceeds to step S16 when thetemperature-retention upper limit S1 becomes equal to the fixed upperlimit S2. This is because the temperature-retention upper limit S1 hasalready reached the fixed upper limit S2 and the temperature-retentionupper limit S1 cannot be incremented any more.

On the other hand, in a case where it is determined in step S12 that theminimum temperature Tmin is larger than the retention determinationtemperature T2 (No in step S12), the processing proceeds to step S17,and it is determined whether the consecutive number N at that time isequal to or larger than the consecutive threshold Nmax.

In a case where it is determined in step S17 that the consecutive numberN is equal to or larger than the consecutive threshold Nmax (Yes in stepS17), the processing proceeds to step S18, and the temperature-retentionupper limit S1 is decremented (subtracted, decreased) by one (S1→S−1).This is because the minimum temperature Tmin consecutively exceeds theretention determination temperature T2 the number of times correspondingto the consecutive threshold Nmax, and it is determined that thetemperature-retention control is sufficiently performed at thetemperature-retention upper limit S1 at that time. Therefore, thetemperature-retention upper limit S1 is decremented in order to supplythe power to the driving of the recording devices as much as possible.

After that, the processing proceeds to step S19, and the consecutivenumber N is reset (initialized, N→zero).

In a case where it is determined in step S17 that the consecutive numberN is lower than the consecutive threshold Nmax (No in step S17), theprocessing proceeds to step S20 without decrementing thetemperature-retention upper limit S1, and the consecutive number N isincremented (added, increased) by one (N→N+1).

After the process in any of steps S15, S16, S19 and S20 is performed,the processing proceeds to step S21 and the temperature-retentioncontrol described with reference to FIG. 6 is executed.

After that, the processing proceeds to step S22 and it is determinedwhether recording of one page has been completed. When it is determinedthat the recording has not been completed (No in step S22), theprocessing returns to step S11, and the minimum temperature Tmin isacquired again from the temperatures detected by the temperature sensors24 a to 24 e within the heater boards HB0 to HB14 of the recording heads105 to 108. After that, the processes in steps S12 to S21 are similarlyrepeated. On the other hand, in a case where it is determined that therecording of one page has been completed (Yes in step S22), the upperlimit calculation processing ends.

As described above, according to the present exemplary embodiment, it ispossible to maintain the driving power of the sub-heaters to be equal toor lower than the fixed upper limit S2 so as not to exceed the powerconsumption taking account of the detection error of the temperaturesensors. Further, since the temperature-retention upper limit S1 isdecremented in the case where the temperature-retention control issuitably performed at the temperature-retention upper limit S1 at thattime, more power can be supplied to drive the recording devices ascompared with the case where the fixed upper limit S2 is constantlyused.

A second exemplary embodiment is described below. In the above-describedexemplary embodiment, all of the heater boards HB0 to HB14 in each ofthe recording heads 105 to 108 are used.

In contrast, in the present exemplary embodiment, only a part of theheater boards HB0 to HB14 in each of the recording heads 105 to 108 isused.

As for parts similar to those in the above-described first exemplaryembodiment, the description is omitted.

In the case where the width of the recording medium P in the Y directionis large, all of the heater boards HB0 to HB14 in each of the recordingheads 105 to 108 are used. Therefore, it is necessary to use all of thetemperature sensors and sub-heaters as described in the first exemplaryembodiment.

In a case where the width of the recording medium P in the Y directionis small, however, the recording medium P may not pass right below, forexample, the heater boards HB0, HB1, HB13, and. HB14 in each of therecording heads 105 to 108 in some cases. In this case, the heaterboards HB0, HB1, HB13, and HB14 are not used for recording, and only theheater boards HB2 to HB12 are used for recording.

At this time, is unnecessary to perform the temperature-retentioncontrol on the heater boards HB0, HB1, HB13, and HB14 in each of therecording heads 105 to 108 because the ink is not in the first placeejected therefrom. Accordingly, in the case where the recoding isperformed on the recording medium P having the small width in the Ydirection, the temperature-retention control illustrated in FIG. 6 andthe upper limit calculation processing illustrated in FIG. 8 areperformed on only the heater boards HB2 to HB12 in each of the recordingheads 105 to 108.

According to the above-described form, it is possible to limit theheater boards to be subjected to the temperature-retention control andthe upper limit calculation processing in the case where the width ofthe recording medium, in the Y direction is small. This excludesconsumption of excess driving power.

A third exemplary embodiment is described below. In the above-describedexemplary embodiments, the temperature-retention control is performedduring the recording operation.

In the present exemplary embodiment, pre-heat control is performedbefore the recording operation is started in addition to thetemperature-retention control.

As for parts similar to those in the above-described first and secondexemplary embodiments, the description is omitted.

In the pre-heat control, the sub-heaters are driven before the recordingoperation is started, to previously increase the temperature in order toprevent the temperature from becoming low immediately after therecording operation is started and to prevent the ejection amount frombecoming excessively low.

Since the pre-heat control is performed before the recording operationis started, the recording devices are not driven at the same timing.Accordingly, the power is not consumed to drive the recording devicesduring the pre-heat control, and substantially all the power consumableby the recording heads 105 to 108 can be used to drive the sub-heatersin the pre-heat control. Therefore, in the pre-heat control, the drivingof the sub-heaters is performed at a pre-heat fixed value S3 that islarger than the temperature-retention upper limit S1 and the fixed upperlimit. S2.

FIG. 10 is a flowchart of the pre-heat control that is executed by theheat control unit 309 according to the control program in the presentexemplary embodiment.

When a recording job is received and preparation for recording start isstarted, the pre-heat control is also started.

When the pre-heat control is started, the temperatures T detected by thetemperature sensors 24 a to 24 e in the heater boards HB0 to HB14 ineach of the recording heads 105 to 108 are first acquired in step S31.

After that, in step S32, it is determined whether each of thetemperatures T detected by the temperature sensors is lower than atemperature threshold T3. The temperature threshold T3 is set to 50° C.in the present exemplary embodiment.

The sub-heater located in a region corresponding to the temperaturesensor, which determines the detected temperature T to be lower than thetemperature threshold T3, is driven in step S33 and heating isperformed. The recording devices are not driven during the pre-heatcontrol as described above. Therefore, even if the driving power of thesub-heaters is increased, excess power consumption does not occur, andthe time required for the pre-heat control is reduced when thesub-heaters are driven with the higher power. Accordingly, thesub-heaters are driven at the pre-heat fixed value S3 that is a highervalue at this time. In the present exemplary embodiment, in the case ofthe pre-heat fixed value S3, the sub-heaters are driven with the SH rank“31” illustrated in FIG. 8.

On the other hand, as for a region corresponding to the temperaturesensor, which determines the detected temperature T to be equal to orhigher than the temperature threshold T3, the temperature issufficiently high. Therefore, the processing proceeds to step S34 andthe sub-heater located at that position is not driven.

After the process of either S33 or S34 is performed in each of thesub-heaters, the processing proceeds to step S35, and the minimumtemperature Tmin of the temperatures T detected by the temperaturesensors 24 a to 24 e within the heater boards HB0 to HB14 in each of therecording heads 105 to 108 is acquired.

The processing then proceeds to step S36, and it is determined whetherthe minimum temperature Tmin is equal to or higher than the temperaturethreshold T4. In the present exemplary embodiment, the temperaturethreshold T4 is set to 40° C. In a case where the minimum temperatureTmin is lower than the temperature threshold T4 (No in step S36), thepre-heating has not been sufficiently performed in a part of theregions. Therefore, the processing returns to step S31 and the processesin steps S32 to S35 for each of the temperature sensors and thesub-heaters are performed. On the other hand, in a case where theminimum temperature Tmin is equal to or higher than the temperaturethreshold T4 (Yes in step S36), the temperature is sufficiently high inall of the regions, and the pre-heat control ends.

As described above, in the present exemplary embodiment, in step S33,the sub-heaters are driven at the pre-heat fixed value S3 that is higherthan the temperature-retention upper limit S1 at the time of thetemperature-retention control described in the first exemplaryembodiment. As described above, according to the present exemplaryembodiment, in a case where the power is not used for driving therecording device, substantially all the consumable power is usable forthe pre-heat control. This makes it possible to reduce the time elapseduntil the pre-heat control ends.

A fourth exemplary embodiment is described below. In the above-describedexemplary embodiments, the temperature-retention control is performedirrespective of the resistance values, the heat dissipationcharacteristics, etc. of the respective sub-heaters.

On the other hand, in the present exemplary embodiment, informationrelating to the resistance values and the heat dissipationcharacteristics of the sub-heaters is previously stored in thesub-heater table storage memory 314, and the temperature-retentioncontrol is performed taking account of the resistance values of therespective sub-heaters.

As for parts similar to those in the above-described first to thirdexemplary embodiments, its description is omitted.

The amount of flowing current is reduced and the driving power becomesinsufficient as the resistance value of the sub-heaters becomes larger.Accordingly, the SH rank is preferably increased, and the driving powerof the sub-heaters is preferably increased.

Further, the heat dissipation characteristics also change depending onthe position in the Y direction in each of the heater boards HB0 toHB14. More specifically, much heat dissipation does not occur at acenter part in the Y direction in each of the heater boards HB0 to HB14.However, the heat dissipation characteristics are high at the end partsin the Y direction because contact area of the substrate and thesupporting member is large. Therefore, at the end parts, even when thesame amount of the power as the center part is supplied to thesub-heaters, generated heat energy is smaller. Accordingly, the SH rankand the driving power of the sub-heaters are preferably increased as theheat dissipation characteristics becomes larger, namely, as thesub-heater is located closer to the end parts in the heater board in theY direction.

Accordingly, in the present exemplary embodiment, a correction value forcorrecting the SH rank is changed according to the resistance value andthe heat dissipation characteristics. Thus, the temperature-retentioncontrol can be suitably performed even if the resistance values aredifferent in each sub-heater or the heat dissipation characteristics aredifferent in each region.

FIG. 11 is a diagram illustrating an example of an SH correction valuetable that is used for calculating an SH rank correction value accordingto the resistance value and the heat dissipation characteristics in thepresent exemplary embodiment. In this example, for the sake ofsimplicity, the SH ranks of the total 15 sub-heaters 23 a to 23 e withinthe heater boards HB0 to HB2 in the recording head 105 of the recordingheads 105 to 108 are illustrated. The SH ranks are similarly determinedfor the sub-heaters of the other heater boards and in the otherrecording heads.

In the present exemplary embodiment, as “deviation of resistance valuefrom reference” in FIG. 11, “0” is determined in a case where theresistance value is not deviated from an ideal resistance value, “−1” isdetermined in a case where the resistance value is slightly lower thanthe ideal resistance value, and “1” is determined in a case where theresistance value is slightly larger than the ideal resistance value.

For example, “−1” is determined as the deviation of the resistance valuefor the sub-heater 23 a of the heater board HB0. This means that theresistance value f the sub-heater 23 a of the heater board HB0 isslightly lower than the ideal resistance value. In addition, “1” isdetermined as the deviation of the resistance value for the sub-heater23 e of the heater board. HB2. This means that the resistance value ofthe sub-heater 23 e of the heater board HB2 is slightly larger than theideal resistance value.

Furthermore, in the present exemplary embodiment, as “heat dissipationcharacteristics from reference” in FIG. 11, “0” is determined in a casewhere heat dissipation hardly occurs, “1” is determined in a case wherethe heat dissipation slightly occurs, and “2” is determined in a casewhere more heat dissipation occurs.

For example, “2” is determined as the heat dissipation characteristicsfor the sub-heater 23 a of the heater board HB0. This means that theheat dissipation easily occurs in the sub-heater 23 a of the heaterboard HB0 because the sub-heater 23 a of the heater board HB0 is locatedat the end part in the Y direction in the heater board HB0.

Further, “0” is determined as the heat dissipation characteristics forthe sub-heater 23 c of the heater board HB0. This means that the heatdissipation hardly occurs on the sub-heater 23 c of the heater board HB0because the sub-heater 23 c of the heater board HB0 is located at thecenter part in the Y direction within the heater board HB0.

As described above, in the present exemplary embodiment, the drivingpower is preferably increased as the resistance value becomes larger andthe heat dissipation characteristics becomes larger. Therefore, thecorrection value of the SH rank is increased in a positive direction.

For example, as for the sub-heater 23 a of the heater board HB0, “−1” isdetermined as the deviation of the resistance value, and “2” isdetermined as the heat dissipation characteristics. Accordingly, thecorrection value of the SH rank is set to “−1” in order to correctinfluence of the deviation of the resistance value, and the correctionvalue of the SH rank is set to “2” in order to correct influence of theheat dissipation characteristics. Therefore, the correction value of theSH rank for the sub-heater 23 a of the heater board HB0 becomes “1” byadding these correction values.

Further, as for the sub-heater 23 c of the heater board HB2, “1” isdetermined as the deviation of the resistance value, and “0” isdetermined as the heat dissipation characteristics. Accordingly, thecorrection value of the SH rank is set to “1” in order to correctinfluence of the deviation of the resistance value, and the correctionvalue of the SH rank is set to “0” in order to correct influence of theheat dissipation characteristics. Therefore, the correction value of theSH rank for the sub-heater 23 c of the heater board HB2 becomes “1” byadding these correction values.

As described above, according to the present exemplary embodiment, it ispossible to suitably perform the temperature-retention control even inthe case where the resistance values and the heat dissipationcharacteristics are different in the sub-heaters.

A fifth exemplary embodiment is described below. In the presentexemplary embodiment, the recording speed is varied according to thesurplus power in driving the sub-heaters.

As for parts similar to those in the above-described first to fourthexemplary embodiments, its description is omitted.

In a case where the density of the recording image is high and it isnecessary to increase the number of driving times of the recordingdevices in recording an image, the driving power is normally increased.In this case, by increasing the recording time, namely, by reducing theconveyance speed of the recording medium P, the number of driving timesof the recording devices per unit time can be suppressed andaccordingly, the driving power can be reduced.

In consideration of the above, for a case where the amount ejectedtoward a certain divided region of the recording medium is large and thenumber of driving times of the recording devices for the divided regionis large, a method for reducing the recording speed and suppressing thedriving power is known.

As described in the first exemplary embodiment, the power which can beused for driving the recording devices depends on thetemperature-retention upper limit S1 that varies in thetemperature-retention control. In other words, when the first exemplaryembodiment is employed, S4=Smax (fixed value)−S1 variable), where theupper limit of the power that can be supplied to the recording heads 105to 108 and the wirings is Smax, and the power which can be used fordriving the recording devices is a driving upper limit S4. Therefore,the power usable for driving the recording devices also varies.

Accordingly, in the present exemplary embodiment, an ejection amountthreshold Dth for determining whether to reduce the recording speed canbe used for driving the recording devices, and the ejection amountthreshold Dth is varied according to the variable driving upper limit S4(=Smax−S1). In other words, in the case where the driving upper limit S4is large, the driving power of the recording devices does not exceed thedriving upper limit S4 even if the ejection amount of the ink is largeor even if the recording devices are driven at the high recording speed.Therefore, the ejection amount threshold Dth is increased in order tosuppress reduction in the recording speed. In this configuration, it canbe more suitably determined whether it is necessary to reduce therecording speed in order to suppress excess power consumption.

FIG. 12 is a flowchart for recording speed setting performed by the CPU306 according to the control program in the present exemplaryembodiment. The speed setting processing in the present exemplaryembodiment is performed every time recording of one page is started.

When the speed setting processing is started, the recording medium isfirst divided in the X direction and Y direction into a plurality ofdivided regions in step S41. The ejection amount D of the ink determinedby the recording data is then acquired for each of the divided regions.

Next, in step S42, the maximum ejection amount Dmax of the ink ejectionamounts D of the respective divided regions, is calculated. The largeamount ejected toward a certain divided region indicates that the numberof driving times of the recording device for the certain divided regionis large. Accordingly, in the divided region of the maximum ejectionamount Dmax the driving power of the recording device is the largest inthe recording of the page.

Next, in step S43, it is determined whether the maximum ejection amountDmax is equal to or lower than the ejection amount threshold Dth. Asdescribed above, the ejection amount threshold Dth is increased as thedriving upper limit S4 becomes larger, and the driving upper limit S4 isincreased as the temperature-retention upper limit S1 becomes smaller.Accordingly, in the case where the temperature-retention upper limit S1is small, the ejection amount threshold value Dth is increased.

In a case where it is determined that the maximum ejection amount Dmaxis equal to or lower than the ejection amount threshold Dth (Yes in stepS43), the excess power consumption does not occur even when therecording speed is increased. Therefore, the processing proceeds to stepS44, and the recording speed is set to 8 ips.

On the other hand, in a case where it is determined that the maximumejection amount Dmax is larger than the ejection amount threshold Dth(No in step S43), the excess power consumption may occur if therecording speed is increased. Therefore, the processing proceeds to stepS45, and the recording speed is set to 3 ips.

After the process in either step S44 or S45 is performed, the speedsetting processing ends.

As described above, the ejection amount threshold Dth for setting therecording speed is varied depending on the temperature-retention upperlimit S1 that is used in the temperature-retention control in thepresent exemplary embodiment. This makes it possible to more accuratelymake a determination whether the ejection amount does not cause theexcess power consumption if the recording speed is increased, or theejection amount may cause the excess power consumption if the recordingspeed is not reduced.

(Other Exemplary Embodiments)

In the exemplary embodiments, the ink of cyan, magenta, yellow, andblack is ejected from separate recording heads 105 to 108; however, theejection may be performed in other forms. The ink of cyan, magenta,yellow, and black may be ejected from one recording head. Further, anejection port array that ejects the ink of cyan, magenta, yellow, andblack may be provided in the same heater board.

In addition, in a mode of the exemplary embodiments, the temperaturesrespectively detected by the temperature sensors 24 a to 24 e within theheater boards HB0 to HB14 of the recording heads 105 to 108 are acquiredin step S11 of FIG. 9 and the minimum temperature Tmin is acquired fromamong the detected temperatures; however, the temperature can beacquired in other forms. For example, from among the plurality ofdetected temperatures, three lower temperatures are acquired, and anaverage temperature thereof may be used as a representative temperaturein the upper limit determination processing, in place of the minimumtemperature Tmin. As described above, the representative temperature maynot necessarily be the minimum temperature Tmin as long as therelatively low temperature is used.

Further, if a region where the temperature is easily lowered ispreviously known, the temperature detected by the temperature sensorcorresponding to the region may be regarded as the representativetemperature in place of the minimum temperature Tmin. For example, inthe case of using the circulation configuration described in theexemplary embodiments, the temperature is easily lowered in a regionlocated on upstream side in the supply direction A and the collectiondirection B of the ink of each of the recording heads illustrated inFIG. 4. This is because, the ink having the temperature lower than theenvironmental temperature in the recording apparatus flows in frontthrough the region on the upstream side in the supply direction A andthe collection direction B. In this case, the temperature detected bythe temperature sensor in the region on the most upstream side in thesupply direction A and the collection direction B in each of therecording heads may be regarded as the representative temperature andused in the upper limit calculation processing, in place of the minimumtemperature Tmin.

In the exemplary embodiments, the upper limit is increased in the casewhere it is determined one time that the temperature is lower than thethreshold, and the upper limit is decreased in the case where it isdetermined a plurality of consecutive times that the temperature ishigher than the threshold. However, when a case where the upper limit isdecreased, and a case where the upper limit is increased, areconsidered, if in the former case the temperature is compared with thethreshold a larger number of times, then similar effects can beachieved. For example, the upper limit may be increased in a case whereit is consecutively determined twice that the temperature is lower thanthe threshold, and the upper limit may be decreased in a case where itis consecutively determined four times that the temperature is higherthan the threshold. In other words, the upper limit may be increased ina case where it is consecutively determined M(M≥2) times that thetemperature is lower than the threshold, and the upper limit may bedecreased in a case where it is consecutively determined N (N>M) timesthat the temperature is higher than the threshold.

Furthermore, in the exemplary embodiments, the recording head larger inwidth than the recording medium is used and the recording is performedwhile the recording medium is conveyed. Alternatively, the recording maybe performed in other forms. For example, a recording operation in whichthe ink is ejected while the recording head scans in a directionintersecting the arrangement direction of the ejection ports, and aconveyance operation in which the recording medium is conveyed in thearrangement direction between the scannings may be repeatedly carriedout, and the recording on the recording medium is completed by scanning(movement) a plurality of times.

In the recording apparatus according to the exemplary embodiments,excess power consumption and insufficiency of the driving power of therecording devices can be suppressed even if the detected temperature andthe actual temperature deviate from each other in the heating operationby the heating devices.

While exemplary embodiments have been described, it is to be understoodthat the invention is not limited to the disclosed exemplaryembodiments. The scope of the following claims is to be accorded thebroadest interpretation so as to encompass all such modifications andequivalent structures and functions.

This application claims the benefit of Japanese Patent Application No.2017-106029, filed May 29, 2017, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A recording apparatus including a recording head,the recording head including a plurality of recording devices containingink, first and second heating devices, and first and second detectiondevices, the recording devices each generating energy for ejection ofthe ink, the first and second heating devices respectively heating theink in a vicinity of recording devices located at first and secondpositions of the recording devices, and the first and second detectiondevices respectively detecting temperatures in the vicinity of therecording devices located at the first and second positions, therecording apparatus comprising: an acquisition unit configured toacquire information relating to a representative temperature of thetemperatures detected by the first and second detection devices; adetermination unit configured to determine whether the representativetemperature or a first temperature threshold is higher; a decision unitconfigured to decide an upper limit of driving power of each of thefirst and second heating devices, based on a determination result of thedetermination unit; a recording control unit configured to drive therecording devices to control a recording operation; and a heat controlunit configured to drive each of the first and second heating devices tocontrol a heating operation during the recording operation, based on thetemperatures respectively detected by the first and second detectiondevices and a second temperature threshold that is higher than the firsttemperature threshold, wherein the heat control unit drives the firstand second heating devices to cause the driving power to be lower thanthe decided upper limit indicated by the representative temperaturerelated information, and wherein the decision unit decides the upperlimit (i) so as to increase the upper limit in a case where thedetermination unit determines one time that the representativetemperature is lower than the first temperature threshold, and (ii) soas to decrease the upper limit in a case where the determination unitconsecutively determines N(N≥2) times that the representativetemperature is higher than the first temperature threshold.
 2. Therecording apparatus according to claim 1, wherein the decision unitdecides the upper limit so as not to change the upper limit in a casewhere the determination unit determines one time that the representativetemperature is higher than the first temperature threshold.
 3. Therecording apparatus according to claim 1 wherein the decision unitdecides the upper limit so as not to change the upper limit in a casewhere the determination unit consecutively determines N−1 times that therepresentative temperature is higher than the first temperaturethreshold.
 4. The recording apparatus according to claim 1, wherein theheat control unit drives the first and second heating devices, based ona difference between each of the temperatures detected by the first andsecond detection devices and the second temperature threshold.
 5. Therecording apparatus according to claim 4, wherein the heat control unitdrives each of the first and second heating devices in a range of thedriving power which is smaller than the upper limit indicated by theinformation, in such a way that the larger the difference, the largerthe driving power.
 6. The recording apparatus according to claim 1,wherein the acquisition unit acquires, as the information relating tothe representative temperature, information relating to a lowertemperature of the temperatures detected by the first and seconddetection devices.
 7. The recording apparatus according to claim 6,wherein the acquisition unit acquires, as the information relating tothe representative temperature, information relating to the temperaturedetected by the second detection device.
 8. The recording apparatusaccording to claim 1, wherein the recording head further includes aplurality of ejection ports, a plurality of pressure chambers, a supplypath, and a collection path, the ejection ports each ejecting the ink,the pressure chambers respectively communicating with the ejection portsand including the recording devices, the supply path supplying the inkto the pressure chambers, and the collection path collecting the inkfrom the pressure chambers, and wherein the second position is locatedon an upstream side from the first position of the supply path in an inksupply direction.
 9. The recording apparatus according to claim 8,wherein the ink in the pressure chambers is circulated between theinside and the outside through the supply path and the collection path.10. The recording apparatus according to claim 1, further comprising asecond heat control unit configured to drive each of the first andsecond heating devices to control the heating operation before therecording operation, based on each of the temperatures detected by thefirst and second detection devices and a third temperature threshold,the second heat control unit driving the first and second heatingdevices to cause the driving power to be larger than the upper limitindicated by the information.
 11. The recording apparatus according toclaim 1, wherein the heat control unit drives the first and secondheating devices, based on resistance values of the first and secondheating devices.
 12. The recording apparatus according to claim 1,wherein the heat control unit drives the first and second heatingdevices, based on heat dissipation characteristics of regions providedwith the first and second heating devices.
 13. The recording apparatusaccording to claim 1, further comprising: a second acquisition unitconfigured to acquire information relating to an ejection amount of theink ejected toward a recording medium; and a setting unit configured toset recording speed in the recording operation, based on the informationacquired by the second acquisition unit and an ejection amountthreshold, wherein the ejection amount threshold is determined based onthe information relating to the upper limit decided by the decisionunit.
 14. A recording apparatus including a recording head, therecording head including a plurality of recording devices containingink, a heating device, and a detection device, the recording deviceseach generating energy for ejection of the ink, the heating deviceheating the ink in a vicinity of recording devices, and the detectiondevice detecting a temperature in the vicinity of the recording devices,the recording apparatus comprising: an acquisition unit configured toacquire information relating to the temperature detected by thedetection device; a determination unit configured to determine whetherthe temperature or a first temperature threshold is higher; a decisionunit configured to decide an upper limit of driving power of the heatingdevice, based on a determination result of the determination unit; arecording control unit configured to drive the recording devices tocontrol a recording operation; and a heat control unit configured todrive the heating device to control a heating operation during therecording operation, based on the temperature detected by the detectiondevice and a second temperature threshold that is higher than the firsttemperature threshold, wherein the heat control unit drives the heatingdevice to cause the driving power to be lower than the decided upperlimit indicated by the representative temperature related information,and wherein the decision unit decides the upper limit (i) so as toincrease the upper limit in a case where the determination unitdetermines one time that the temperature is lower than the firsttemperature threshold, and (ii) so as to decrease the upper limit in acase where the determination unit consecutively determines N(N≥2) timesthat the temperature is higher than the first temperature threshold. 15.A recording apparatus including a recording head, the recording headincluding a plurality of recording devices containing ink, first andsecond heating devices, and first and second detection devices, therecording devices each generating energy for ejection of the ink, thefirst and second heating devices respectively heating the ink in avicinity of recording devices located at first and second positions ofthe recording devices, and the first and second detection devicesrespectively detecting temperatures in the vicinity of the recordingdevices located at the first and second positions, the recordingapparatus comprising: an acquisition unit configured to acquireinformation relating to a representative temperature of the temperaturesdetected by the first and second detection devices; a determination unitconfigured to determine whether the representative temperature or afirst temperature threshold is higher; a decision unit configured todecide an upper limit of driving power of each of the first and secondheating devices, based on a determination result of the determinationunit; a recording control unit configured to drive the recording devicesto control a recording operation; and a heat control unit configured todrive each of the first and second heating devices to control a heatingoperation during the recording operation, based on the temperaturesdetected by the first and second detection devices and a secondtemperature threshold that is higher than the first temperaturethreshold, wherein the heat control unit drives the first and secondheating devices to cause the driving power to be lower than the decidedupper limit indicated by the representative temperature relatedinformation, and wherein the decision unit decides the upper limit (i)so as to increase the upper limit in a case where the determination unitconsecutively determines N(M≥2) times that the representativetemperature is lower than the first temperature threshold, and (ii) soas to decrease the upper limit in a case where the determination unitconsecutively determines N(N>N) times that the representativetemperature is higher than the first temperature threshold.
 16. Arecording method for recording with use of a recording head including aplurality of recording devices, first and second heating devicescontaining ink, and first and second detection devices, the recordingdevices each generating energy for ejection of the ink, the first andsecond heating devices respectively heating the ink in a vicinity ofrecording devices located at first and second positions of the recordingdevices, and the first and second detection devices respectivelydetecting temperatures in the vicinity of the recording devices locatedat the first and second positions, the recording method comprising:acquiring information relating to a representative temperature of thetemperatures detected by the first and second detection devices;determining whether the representative temperature or a firsttemperature threshold is higher; deciding an upper limit of drivingpower of each of the first and second heating devices, based on adetermination result in the determination; driving the recording devicesto control a recording operation; and driving each of the first andsecond heating devices to control a heating operation during therecording operation, based on the temperatures respectively detected bythe first and second detection devices and a second temperaturethreshold that is higher than the first temperature threshold, whereinthe first and second heating devices are driven to cause the drivingpower to be lower than the decided upper limit indicated by therepresentative temperature related information in the heat control, andwherein, in the decision, the upper limit is decided (i) so as toincrease the upper limit in a case where it is determined one time inthe determination that the representative temperature is lower than thefirst temperature threshold, and (ii) so as to decrease the upper limitin a case where it is consecutively determined N(N≥2) times in thedetermination that the representative temperature is higher than thefirst temperature threshold.